PHOENIX » Jared L. Loughner’s grandparents and great-grandparents died years ago, but lawyers defending Loughner in connection with a Jan. 8 shooting spree outside Tucson are delving into their lives and those of numerous other Loughner ancestors in an apparent effort to show that mental illness runs in the family.

A raft of subpoenas that Reuben C. Cahn, one of Loughner’s lawyers, issued last month, and then withdrew, indicates that the defense is researching the backgrounds of many of the defendant’s relatives from Illinois, all on his mother’s side.

In May, Loughner was found mentally incompetent to stand trial on charges that he murdered six people and tried to kill 13 others at a constituent event for Rep. Gabrielle Giffords, who was shot in the head. A federal district judge, Larry A. Burns, scheduled a hearing for Sept. 21 to determine whether Loughner, who is being held at a federal psychiatric facility in Springfield, Mo., has improved enough to understand the 49 federal charges against him and assist in his defense.

The prosecution has described how Loughner has thrown chairs and spat at one of his defense lawyers while in custody. He has had such difficulty sleeping that he has been awake for as many as 50 hours at a time, according to court records, which also describe him as being on suicide watch and as pacing in his cell so much his legs have swelled.

The birth and death records that the defense sought from the Division of Public Records at the Illinois Department of Public Health go as far back as 1893, when one of Loughner’s maternal great-grandmothers, Mary Johnson Totman, was born. It was not certain whether similar attention was being paid to his paternal lineage.

Loughner, who turns 23 next month, is the only child of Randy and Amy Loughner. His second cousin Judy Wackt, one of 22 relatives whose records were subpoenaed by the defense in Illinois, described after the January shooting how her mother and one of her aunts had experienced extreme bouts of mental illness.

"There’s a history in the family of what they used to call manic depression, which I guess they now call bipolar disorder," Wackt, who lives in Texas, told The Washington Post. "My mother battled depression. One of her sisters had extreme bouts. She’d be OK, then she’d dissolve over time. Wouldn’t leave the house. Wouldn’t bathe. Wouldn’t interact with her husband or children."

Reached Monday, Wackt said, "I’ve spoken to his attorney and the psychiatrist for his defense team, and I’ve said all I want to say."

At a hearing in May, Loughner’s parents, who were in the courtroom, sobbed when the judge recounted that experts believed that the defendant’s mental health had been in decline for two years before the shooting.

In their only public comment since the crime, which horrified the nation, the Loughners issued a brief statement saying, "We don’t understand why this happened."

Legal experts consider the attention on Loughner’s relatives part of his defense team’s effort to bolster an eventual insanity defense or to argue against the death penalty.

"If the defense can show that mental illness runs in the family, they have a stronger case, one that is more convincing to the jury," said Christopher Slobogin, a professor of law and psychiatry at Vanderbilt Law School. "Short of a brain scan that shows mental defect, a family history of mental illness is the most persuasive evidence that someone had significant mental problems at the time of the crime."

Cahn, one of Loughner’s defense lawyers, did not respond to a request for comment. Neither did Laura E. Udall, who appeared in court with Loughner’s parents.

The defense later withdrew the subpoena to the state of Illinois, a spokeswoman for the state said, but court documents indicate that defense lawyers intend to reissue the demand for records. The U.S. Attorney’s office in Phoenix objected last week to Loughner’s lawyers’ issuing subpoenas without the approval of the court and called on Burns to quash any pending subpoenas.

Two mental health experts have diagnosed schizophrenia in Loughner. Because he has been determined a threat to himself and others, Bureau of Prisons psychologists have been forcibly medicating him, which his defense team has strenuously objected to in a series of court filings.

Loughner’s lawyers have asserted that prison officials may be administering medication to their client so they can prepare him to face the death penalty.

"Mr. Loughner has a due-process right to bodily integrity free of unwanted, forcible administration of psychiatric medication," his lawyers wrote in a recent request for a court hearing on the matter.

Loughner’s lawyers have also urged the court to order the videotaping of Loughner’s interviews with prison psychologists. They say he suffers from a condition called echolalia, which makes him repeat whatever is said to him, that the defense wishes to monitor.

© 2011 The New York Times Company